The answer to your question is yes. The above scene is, as the insert shows, only illuminated by a single spotlight that's aimed at a cube above the frame. The ambient light is set at zero. Antialiasing is fast, object accuracy is 2 pixels, shadow at 4, and indirect lighting is enabled, lighting quality at fast and accuracy at 16 pixels. Even with these default, fairly low quality settings, this simple sphere took about 6 minutes to render.

But, damn, GI looks good!